Phivolcs: better instruments needed to identify faultlines


Posted at Feb 08 2012 03:05 PM | Updated as of Feb 09 2012 04:36 AM

MANILA, Philippines - Some areas in Visayas can expect more frequent seismic activities, the Philippine Institute of Volcanology and Seismology (Phivolcs) said.

This, after an active but previously unmapped fault along the stretch of Negros generated Monday's earthquake.

More than 1,200 aftershocks have been recorded, but Phivolcs describes this situation as normal for a magnitude 6.9 quake.

“There will always be aftershocks after a big activity. We expect a lot of earthquakes as part of the adjustment being done because the rupture zone extends 50 to 80 kilometers, that means it has moved, some areas are compressed some areas are dilated. That means they are adjusting until such time its stabilized,” said Ishamel Narag, officer-in-charge of Phivolcs’ Seismology Division.

Narag said better instruments and improved digital seismographs located near the epicenter helped detect the quake's location.

He, however, admitted there is still a need for high-resolution topographic maps to improve the agency's identification of fault lines.

“What we need is high resolution topographic maps to identify any fissures on the surface that would indicate past rupturing. We couldn’t find an active fault responsible for this earthquake so we decided its possibly an unmapped fault that is lining across coast of Negros,” he said.

Architect Felino Palafox, meanwhile, said aside from doing the hazard-mapping and specifying the location of fault lines, government should also identify areas subject to liquefaction.

Palafox said government should update its land use, zoning and building codes, identify sites for proposed evacuation, and ensure infrastructure and homes are built to withstand quakes.

“You should never build on top of a fault line. You can build 5 meters away from it but some buildings were allowed to be build on top of it. I think immediately now structures on top of fault lines should be removed or relocated right away,” Palafox said.

Palafox also suggested that government put up warnings near fault lines so that the public will be aware they are in a danger zone.

“I think they should already put monuments near the fault lines. In California, it's even a tourist attraction. How come Philvocs or the government agencies don’t put monuments to mark where the fault line is. Elsewhere in the world, they mark where fault lines are,” Palafox said.

Narag said Phivolcs has done this but the project was short-lived.

Palafox and Narag agreed government should work closely with scientists and urban planners so that more helpful maps could be produced.

They also stressed the need for the enactment of more laws that will raise safety standards in areas that are vulnerable to earthquakes. - ANC